1. Field of the Invention
This invention relates to a process for converting particles of magnetite ore grit into magnetic spheres by melting the grit in an arc heated gas jet.
2. Description of the Prior Art
Tiny spheres of about 100 mesh or less, of magnetite ore (Fe.sub.3 O.sub.4) are useful in various industrial processes. Heretofore the pheres have been produced by an alternate process of atomizing and freezing which process has had the disadvantage of difficulty of control of particle size of the product, resulting in low product yield. From time to time apparatus and methods for chemically treating materials, such as ores, by plasma arc heaters have been disclosed in the prior art; i.e. in U.S. Pat. Nos. 3,661,764, 3,708,409 3,749,763, and 3,811,907. Such apparatus and methods are unsuitable for the production of magnetite spheres, because they include the use of carbon-containing electrodes which if contacting by magnetite (Fe.sub.3 O.sub.4) result in a chemical change of the Fe.sub.3 O.sub.4 and of the electrodes. Other electrodes comprised of metals such as tungsten are also destroyed by Fe.sub.3 O.sub.4, and, in addition, require the use of inert gases to maintain the integrity of the electrode. Accordingly, there is a need for an alternate method of producing magnetite spheres that would be conducive to a continuous yield of the desired particle size.